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TDC1000: Calculation of TOF used in TDC1000-TDC7200EVM module

Minrak Kim
Intellectual 320 points
Part Number: TDC1000

Hello, I am Minrak and I work in KIST (Korea Institute of Technology).

I really appreciate your replies regarding the ultrasonic module as I got replies several times before. 
I am working on ultrasonic sensor to get differential liquid height and I need to calculate TOF value given by GUI.

I am using short TOF mode as it gives me less scattering for my application. 
Please go through the six questions as below and give me replies. I will really appreciate your help.

Please tell me if you have anything to clarify.

Best regards,

Minrak Kim

  • 0
    TI__Expert 3450 points

    Hi Minrak,

    To adjust the device settings according to your measurement parameters, the expected ToF should fall within the time: C + D + E, assuming TOF_TIMEOUT_CTRL is enabled. 

    1) Given the formulas for T0 and T1 above, T0 is controlled by the CLOCKIN_DIV register setting, which is a value of 0 or 1, meaning that f0 is either the same as f_clockin, or f_clockin/2. Similarly, T1 is controlled by TX_FREQ_DIV, which is the register setting that controls the transducer excitation frequency. In the default device and GUI case, f_clockin is 8MHz, T0 = 1/8MHz (CLOCKIN_DIV=0), T1 = 1/1MHz (TX_FREQ_DIV=2). 

    2) I recommend leaving AUTOZERO_PERIOD as the default value.  

    3) Yes, your example for NUM_TX*T1 is correct. 

    4) SHORT_TOF_BLANK_PERIOD determines the length of time before the listen period begins. This should be customized to your expected delay. Also, note that this settings may require some experimentation to obtain a good ToF result. 

    5) TOF_TIMEOUT_CTRL adjusts the listening period. This should be set based, along with SHORT_TOF_BLANK_PERIOD, based on the expected range of ToF measurements to be made using the same device settings, and the measurement frequency. Use the formula to determine the value for TOF_TIMEOUT_CTRL, and make sure that ECHO_TIMEOUT is enabled to use this setting. 

    Regards,

    Gabriel